Reproducing half-tone printing plates



' rinting plates,

Patented Nov. 3,

UNITED STATES PATENT OFFICE.

nnwnn'n. xUNz, or wrmmr'raimmoxs.

mBODOING HALF-TONE PRINTING PLATES.

Application mail Ily 8,

To all whom it may concern.' v Be it known that I, EDWARD A. KUNz, a citizen of the United States, resdin at Wilmette, in the county of Cookand tate of Illinois, have invented certain new and useful Improvements in Repoducing Half- Tone Printing Plates, of w 'ch the followin is a specification. f

e present invention relates to im rovements in reproducing half-tone printing plates.

More particularly, the present invention relates to rocesses for makin enlarged copies or uplicatesaor reduce copies of so-called hal -tone, line or color process one object of the invention in to materially reduce the cost of repro ucin said plates.

Accordmgto present practice, when it is desired to reproduce a printing plate, an entirel new photograph is made on the scale esired, which photograph is applied to the printing plate and subjected to the etching process. For various reasons, which need not be recited in detail herein, the etched plate must be nished by means of very laborious and expensive hand work in order to brin out the proper tones, values, detail, etc. ccording to the processes as now known and used, the production of any subsequent plates is practically as expensive as the reduction ot the first printingplate. Accor ing -to the present invention, however, a very considerable saving is accomplished in the production of subsequent printing plates in a manner which will be clear as the description proceeds. The resent invention is employed more particuarly fin the making of enlarged plates, thou h, it will be understood, it is also applicale to the reproduction of printing plates on any desired scale. The one figure of the drawing represents, on an enlarged scale, a cross sectional view of a half-tone printing plate and an inking roller illustrating the rinciples of the present invention. Accor ing to the present invention, after the original rinting plate has been made, subsequent p ates may be produced substantially accor-din to the rocesswhich may be described as fo lows: Flrst the original plate is thoroughly cleaned with acid, ye, water, or other cleaning agent to remove all foreign substances, leaving the metal perfectly clean. A tine white magnesia or French chalk is rubbed into depressions or bottoms until all 1922. serial no. 559,435.

the gradations of color, detail, design and the' l1ke are clearly defined, the printing surface being rubbed and cleaned so as to bc free from chalk, that is to say, the projecting portions, or printin surface, of the plate are cleaned while t e depressions are covered with the chalk. The chalk may then be hardened b any of the well known processes for t at purpose and the late maybe rolled up with ink, usually b ack. Particular attention should be directed to the advantages of hardenin the chalk, or other substance located in t e depressions or bottoms. The hardenin process will not only facilitate ease in han ling the printing .plate but has the further advanta e that the chalk lor other substance in the epressions or bottoms will shrink slightly, whereby the printing dots will be cleanly presented. The printing surface will reject slightly above the sur ace of the chal whereby the printing surface, and only the printmg surface, is evenly covered-with ink. A picture is thereby created in black and white of the subject which appears on the plate, which picture is now ready for hotographing. The prepared plate is now pliotographed to the desired size for the new late, the resulting 4photograph being app ied to a sensitized blank and subjected to the etching process. Any line, dot or detail appearing on the original plate will be reproduced upon the new plate. It will be understood that though magnesia -or chalk, which are white in color, and ink, which may be black, are mentioned herein, other materials'may be used, provided they contrast photographically. v

The approved process according to the,

present invention is especially-deslrable in the making of enlarged printing plates from the so-called colortype or three or four color process engravings.v Inasmuch as all details of the original plate. are sharply defined in the new plate, subsequent manipulation is minimized, whereby the cost of reproducing the original plate'is reduced to a minimum.

The resentinvention istobedistinguished from t e process of photographing a proof made by the original plate and using the resulting photograph by applying same to the printing plate under preparatlon. This process has been found to be objectionable for the reason that same isinaccurate.

One embodiment of the present invention lus has been described in detail. Man 1 modiin the fications will occ'ur to those skille art.v It is intended in this patent to cover all` such modifications that fall within the scope of the invention as defined by the appended claims. v

I claim:

1. Steps in the improvedprocess of reproducing a printin plate consisting in rubring chalk upon sai plate to fill up the deluressions thereof but leavin the printing surface clean, hardening sai chalk, rolling up the printing surface With black ink and hotographing the treated plate. l

A step in the process of reproducing a printing plate which consists in thoroughly cleaning same and rubbing chalk into the ldepressions thereof but leaving the printing chalk.

3. The improved process relati l l'arly to the enlar ement of rintmg plates which consists in lling the @pressions in a 25 printing plate with one substance, harden mg said one substance, and covering the printing surface with a substance contrast'- ing photographically with the rst mentioned substance, photographing the treated 80 plate and using the resulting negative for the production of a new plate.

Signed at Chicago, Illinois, this 284th day y l of April, 1922.

EDWARD A. KUNz. 

